The overabundance of cyanobacteria and of algae in stagnant waters, known as eutrophication of water, is a worldwide problem, especially because of the fact that vegetative secretions of cyanobacteria are toxic.
Currently, cyanobacteria in stagnant waters of lakes and dams are disposed of by means of biomechanical equipment using float structures, built on the principles of biological reduction of phosphorus and nitrogen in water by cultivating special aquatic plants. The disadvantages of these devices are low efficiency, requirement of taking care of plant growth and limitations due to the vegetation period of plants—E 10822, WO2009030977 (A2).
Also known are facilities for mechanical disposal of cyanobacteria, on the principle of dredging the bottom of water reservoirs from their banks, or by using water-born dredgers. This technology is expensive and has only a short-term effect because reproduction of cyanobacteria is dependent on the content of phosphorus and nitrogen in water, which are not eliminated by these devices—FR20000000046, FR2791947 (A3).
Also used are technologies on chemical or biological principles, by means of equipment on the principle of dispensers—WO9938810 (A1). However, disposal of cyanobacteria by chemical treatment of water destroys biological life in the water in its entirety, thus also affecting macrological forms of life. The most common way of limiting the growth of cyanobacteria in water reservoirs is the application of toxic substances for cyanobacteria and algae—the use of algicidal or algistatic substances. Although the advantages of this method are its relatively easy application and low time consumption, it is not possible to determine in advance, whether such intervention will be effective, environmentally friendly and economically advantageous.
Devouring of cyanobacteria by natural predators is rare and is restricted, for example to the use of cyanophage viruses, also of bacteria, such as actinomycetes and flexibacter, which affect the cell wall of the cyanobacterium, thus preventing photosynthesis, however, the secondary effects of this method are unexplored yet. Using algae, fungi and protozoa also disrupts the overall biodiversity of waters and is not effective—DE19731309 (A1).
Cavitation is also a well-known method of disposal of cyanobacteria from the bottom of reservoirs.